FR2555699A1 - SEAL FOR HIGH PRESSURE - Google Patents

Abstract

THE INVENTION RELATES TO A SEAL FOR HIGH PRESSURES, IN PARTICULAR A SHAFT SEAL. IT INCLUDES A METAL BODY 12 ON WHICH A PART 14 OF ELASTOMER IS FIXED. THE BUILDING IS CONFIGURED SO AS TO AVOID CONCENTRATIONS OF STRAIN IN THE AREAS OF FIXING OF THE ELASTOMER PART 14 TO THIS BUILDING WHEN HIGH PRESSURES ARE APPLIED TO THE JOINT. FIELD OF APPLICATION: OIL SEALS, ESPECIALLY FOR MOTOR SHAFTS, ETC.

Description

The invention relates generally

  seals for fluids designed for work-

  ler in ambient environments at high pressure.

  The seals currently used in the petroleum industry are often placed

  under very harsh ambient conditions of use.

  They must seal against very low viscosity fluids and must ensure their

  service under high temperatures and pressures.

  Seals for use in

  special circumstances such as the automobile,

  farming, aeronautics or other power steering devices, as well as other

  hydraulics under high pressure, are designed to

  be both rotational movements and reciprocating movements and to establish a pressure balance so that increased pressure tightly applies the sealing lip against the element to be sealed, but nevertheless allows the desired movement, without undesirable friction or deterioration

of the seal.

  Such seals often comprise other members such as rings or reinforcing rings made of a dimensionally stable material, and these members are also often supported or positioned by rings,

  collars, washers or other metallic elements.

  Seals of this type are

  advantageously of an appropriate design with regard to

  It includes pressure balance, pre-delivery lubrication, tailored lip and springs, adjustment tolerances and the like. However, although great progress has been made, to the point that tightness can be ensured in many applications for several years, without difficulty, while allowing operation under pressures of 4.9 to 10.5 MPa and all by also allowing rotational movements and reciprocating movements, without significant loss of fluid, we began to notice failures of joints

  sealing in other parts of these seals. accordance

  In accordance with the invention, a seal frame or seal may be adapted for use with existing molding processes, but

  so as to minimize or eliminate concentra-

  undesirable constraints on the transition zones between a supported part and a part

  unsupported elastomer seal.

  In many high-pressure seals, it has been found that high pressure causes failures at the location where the force

  content tends to separate the non-supportive elastomeric

  building, near its inside diameter,

  at a sharp edge formed by piercing

of the frame element.

  Since the replacement of a defective seal requires work and causes disruption of a cost substantially greater than that of the seal itself, it has been asked for seals having an extended service life and in particular joints that are not likely to be quickly destroyed or deteriorated in

work under high pressure.

  An improved seal with a profiled frame or stiffener, designed not to fail under any

high pressure.

  The seal of the invention is designed to balance the shear forces and other destructive forces generated in the finished seal when subjected to high pressure applications by the use of a frame having a inner edge which has an increased surface, a connecting bead of profiled cross section, of smooth outer profile and surrounded entirely by

  parts of the lip body of the joint.

  The invention also relates to a seal frame adapted to receive a bonded lip portion and which may be made without the use of unusual or expensive tools. The invention will be described in more detail with reference to the accompanying drawings by way of non-limiting examples and in which: - Figure 1 is a perspective view of the seal according to the invention, showing the main elements of this seal ;

  FIG. 2 is a vertical section through

  the seal according to the invention, in the state as manufactured; - Figure 3 is a section similar to that of Figure 2, showing the seal in the installed position of use on an associated shaft forming part of the mechanism to be sealed; FIG. 4 is a vertical section of a

  part of a seal of the prior art, illustrated

  the disadvantages of such seals when used in high pressure ambient environments; - Figure 5 is a section similar to that of Figure 4, but on an enlarged scale, further illustrating the disadvantages of seals of the prior art; and

  FIG. 6 is a vertical section through

  also on an enlarged scale, showing the advantages

  ges and characteristics of the seal frame

according to the invention.

  The description will relate to a form of

  relatively simple embodiment of a seal designed to be used in a high pressure environment and represented without conventional auxiliary member such as reinforcing rings, springs or

anti-extrusion elements.

  Referring in more detail to the drawings,

  FIG. 1 represents a device or seal 10 of

  which comprises a portion 12 forming a rigid frame

  and an elastomeric portion 14 and, for the purposes of

  This portion 14 is subdivided into a mounting bead portion 16 defining the outside diameter of the rubber seal, an intermediate body 18 and a lip body 20. The latter is itself subdivided into a main lip body 22, a stop lip or auxiliary lip body 24, and a part

26 of liaison.

  The frame 12 comprises an axial flange 28 situated radially on the outside, serving as a mounting support part, a bent or rounded part, a flange 32 extending radially and a part

  inner 34 for the connecting bead.

  Coeformint to the invention, the part 34 of bead of

  assembly comprises a first mtaliclinée 36.

  folded to another thickness 38 along a bend, the second inclined metal thickness 38 leading to an inner edge 42.-bSti as a whole thus comprises the flanges 28 and 32, while the flange 32 has an inner edge 44 having opposed surfaces 46, 48, on the oil side and the air side, respectively turned towards the zone to be sealed and towards the opposite side to that zone. In this

  description, the expressions "internal axial", or "axial

  "Inward direction" means in the direction of the area to be sealed, that is to the right in the orientation of Figures 2 and 3, for example, except for the edge 44 having the surfaces 46 and 48, the frame 12 (see FIG. 6) comprises the annular connection bead 34 which has an inwardly directed flange surface 50, an adjacent flange surface 52 directed radially inwardly of the inside diameter of the seal, and an inclined surface 54 which is directed radially inwards, but

  also somewhat axially outward.

  The lip-forming body portion 20

  In fact, it can be considered as beginning at the lower part of the web 18 where it is bound to the marginal surface 46, and as being continuously bonded around the perimeter of the curvilinear surfaces respectively.

  50, 52 and 54. The body also covers, preferably

  The inner edge 42 of the frame 12 as well as the marginal surface 48, directed axially outwardly of the frame 12. Consequently, the lip body is bonded to the frame according to a continuous curvilinear annular bead of increasing cross section relative to the section of the remaining part of the stamped element. The inclined marginal flanges 36, 38 of the bead are shown as being bent in order to actually apply one on

  the other or to be adjacent to one another, although

  they can simply extend in close proximity to one another and be slightly spaced from each other, provided that the radially inner portion of the frame has the profiled edge which is free of sharp edges on the whole surface. extent of the body exposed to pressure

  high in the seal frame.

  The frustoconical lip surfaces 56, 58, located on the so-called oil-side and air-side sides, meet substantially in a cylinder to form a sealing strip 60 for making a main contact with an associated shaft.

  (Figure 3) or other sealed element.

  The lip body also has a groove 64 designed to accommodate a spring 66, the auxiliary lip or exclusion lip 64 being formed by axially extending surfaces.

inner and outer 68, 70.

  Referring now to FIG. 3, the seal according to the invention is shown in the position of use in which the band 60

  seal is in close contact with the external surface

72 of the shaft 62.

  In this figure, the auxiliary or secondary lip 24 is shown in contact with the surface 72 of the shaft, only under slight pressure, and is therefore not deformed, while the zone 22

  of the main lip is represented as being

  substantially deformed, it being understood that the seal, in the intended application, is subjected to a high pressure prevailing in the generally indicated area

  by reference 77 in FIG.

  Figures 4 and 5 show a seal 10a of the prior art which comprises a frame 12a and a lip body 22a, similar to those of the seal according to the invention. In FIGS. 4 and 5, the stress concentration zones are schematically illustrated at points "X" and "Y" and it can be seen that the rubber body is shown during separation along the sharp edges "Z" of the inner edge

of the joint frame.

  It has been found that seal failure often occurs in this area and appears to be due to the application of pressure.

  extremely high levels, in particular of intermittent pressures

  tents, as indicated by the arrows in FIG. 5. These forces tend to deform the elastomer radially inwards in the zone of the inner edges of the

  12a of the seal, which leads to a tear-primer

  or rupture of the bond or elastomer

near the link.

  As time passes, the stress concentrations in this area continue and cracks or rips spread along the circumference of the building and eventually progress

  outward, as shown, in the joint body.

  This leads to an increase in bending and deformation with, as a result, worsening of the seal deterioration, followed by premature failure. Therefore, although it is expected that seals of this type will suffer the most

  wear in the immediate vicinity of the water surface

  In this case, it is found that these joints are often subjected to undesirable movement sequences, including excessive deformation, due to the failure of the connection between the shaft and the joint. body and the inner parts of the joint frame. This seems to be due to the presence of sharp edges and angles surfaces

  rights in the vicinity of enforcement enforcement points

important.

  In addition to the radial stresses indicated diagrammatically on the arrows in FIG. 5, there are also circumferential stresses

  which appear in joints of this type, these contrain-

  usually occurring when the seal is subjected to intermittent movements or start-stop movements, the seal body then establishing a "glue-slip" relationship with the shaft it

  protects and this, as a result, generates a circumferential

  of cutting or shearing in the body of the

  seal, causing premature failure.

  With reference again to the seal according to the invention, FIG. 6 shows that the frame has, in accordance with the invention, a profiled inner edge.

  to spread the stresses in this area and to eliminate

  the elevations or stress concentrations.

  Consequently, with reference to FIG. 6, these surfaces 52 and 54 are connected to one another following

  a progressive curve and the stresses are uniform-

distributed in these areas.

  In most cases, the mounting bead, in the form shown or in a similar form, provides about two times and dmies the bonding surface of most currently embossed designs. As a result, the resistance to deterioration under pressure is increased. In addition, by using a continuous sealing body which comprises a mounting bead 16 and the intermediate body or the core 18, any pressed interface / visible joint is eliminated.

  which would itself be a constraint concentrator.

  In other words, the parts of the joint exposed to high pressure comprise only the parts

  covered with rubber and not a line according to which

  the apparent part of the embossing is related to the rubber

  Chouc. The design of the gasket according to the invention thus eliminates the zones in which it generally starts.

the failures of the joints.

  It goes without saying that many modifications can be made to the joint described and shown

  without departing from the scope of the invention.

Claims (11)

  1. Seal for high pressure, characterized in that it comprises a frame (12) and a portion (20) sealing lip, the frame comprising at least a first flange (28) to be placed at immediate proximity of a part of an associated mechanism to sealingly protecting, to place the seal in a mounting and operating position, a flange (32) extending approximately radially, connected to the first flange and intended to extend over a part of an opening and to close this opening defining a part of an area to be sealed, in which a fluid can be retained under pressure, said radial flange also having a first internal marginal surface (46) directed towards the area to be sealed, and a mounting bead (34) located radially inwardly and profiled to have an enlarged section relative to that of the remaining portion of the frame, the bead having a smoothly curved continuous connecting annular surface which includes a first portion (50) oriented generally towards the side of the fluid-facing seal, and a second intermediate portion (52) connected to the first part and oriented globally towards the inside diameter of the opening defined by   the Joint, and a third part (54) connected to the second   I portion and turned at least partially away from the side of the fluid and outwardly from the sealingly protected area, the sealing lip portion being made of elastomer and comprising a main sealing lip body (22) having the first and second substantially frustoconical surfaces (56, 58) respectively at least partially facing the sealed zone and towards the opposite side thereof and joining to define a circumferential band (60) main sealing element intended to be in contact with an associated shaft (62) or other part to be sealed, the joint also comprising a connecting part which completely surrounds the first, second and third surfaces   of the frame and which is linked to these surfaces.   Seal according to claim 1, characterized in that the sealing lip portion further has surfaces which define an axially extending exclusion auxiliary lip (24).   the outside of the main lip.   3. Seal according to claim 1, characterized in that the sealing body further comprises an annular core (18) made of a material   part of which is linked to a radially inte-   (44) of an axially oriented portion of said radial flange of the frame.   4. Seal according to claim 1, characterized in that a cylindrical body (16) of elastomer forms the outer diameter of the seal and extends   on the outer surface of the axial flange of the frame.   Seal according to claim 1, characterized in that the sealing lip portion is further integrally formed with a portion (18) extending radially outwardly and longitudinally. a portion oriented axially and inwardly of said radial flange of the frame to which it is bound. Seal according to claim 1, characterized in that the sealing body further has an annular groove (64) for a spring (66) and located approximately in radial alignment with   the main sealing strip.   7. Seal according to claim 1, characterized in that the sealing body further comprises an auxiliary sealing lip (24) axially spaced outwardly of the main sealing strip. 8. Seal according to claim 1, characterized in that the bead of the frame comprises first and second thicknesses (36, 38) made of the material forming the frame, these thicknesses being interconnected by an elbow (40). and the second thickness terminating in an upwardly bent frame edge (42), the seal body further comprising a portion that completely surrounds the curved edge toward   the top of the frame and which is linked to this edge.   9. Oil seal, characterized in that it comprises a lip portion (20) sealing elastomer and a frame (12) made of rigid material and comprising a flange (28) mounting, a flange radial (32) offset and inner annular bead   (34) formed by folding at least two thicknesses   the first and second inclined portions interconnected by an elbow (40), one of said thicknesses terminating in an edge (42); ) and the elbow   with a globally rounded outer surface   to the area to be sealed and to the inside diameter of the seal, said lip portion having surfaces (56, 58) facing the air and to the oil and meeting one circumference to define a band ( 60), another portion being bonded to an inner edge of the radial flange of the frame and completely surrounding this inner edge and the outer surfaces and a portion of the edge of the thicknesses forming said bead to provide a bonding surface designed to resist failures   under the application of high pressure.   10. Oil seal according to claim 9, characterized in that the sealing lip portion further comprises an additional body (18) formed integrally therewith and having a connecting surface extending along the flange   offset of the frame and linked to this flange.   11. Oil seal according to claim 9, characterized in that the sealing lip portion further comprises an auxiliary exclusion lip (24) extending axially outwardly. the sealing strip.